MIAMI, August 5, 2026
Summit Therapeutics announced the launch of the Phase II/III HARMONi-GU1 study, the company’s first global registrational clinical trial evaluating ivonescimab in first-line locally advanced or metastatic urothelial carcinoma (bladder cancer). The trial will compare ivonescimab plus enfortumab vedotin (EV) against the current standard-of-care combination of pembrolizumab plus EV in approximately 800 patients. Global clinical trial site activations are expected to begin in Q4 2026, with the Phase III portion evaluating progression-free survival (PFS) and overall survival (OS) as primary endpoints. The study marks the first global genitourinary cancer program for ivonescimab and further expands Summit’s international oncology development strategy
Ivonescimab Development Program Expands Across Multiple Solid Tumors
The initiation of HARMONi-GU1 strengthens Summit Therapeutics’ rapidly expanding global clinical program for ivonescimab, a potential first-in-class PD-1/VEGF bispecific antibody engineered to simultaneously block immune evasion and tumor angiogenesis. The investigational therapy is now being evaluated across 16 Phase III clinical trials covering non-small cell lung cancer (NSCLC), colorectal cancer (CRC), pancreatic cancer, head and neck cancer, kidney cancer, and bladder cancer. According to the company, four completed Phase III studies have already reported positive efficacy data in NSCLC, supporting continued expansion into additional tumor types with significant unmet medical needs.
Novel Bispecific Antibody Targets PD-1 and VEGF in a Single Molecule
Ivonescimab combines PD-1 immune checkpoint inhibition with VEGF blockade within a single tetravalent bispecific antibody, aiming to improve anti-tumor activity while maintaining a manageable safety profile. Summit stated that the molecule’s cooperative binding design enhances activity within the tumor microenvironment, potentially delivering deeper and more durable responses than existing therapies targeting either pathway alone. The HARMONi-GU1 trial will evaluate whether this dual-targeting mechanism can improve clinical outcomes in patients with previously untreated advanced urothelial carcinoma, where long-term survival remains limited despite recent therapeutic advances.
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Summit Advances One of Oncology’s Largest Global Bispecific Programs
With the addition of HARMONi-GU1, Summit Therapeutics continues building one of the largest global clinical development programs for an investigational bispecific antibody. More than 4,000 patients have received ivonescimab in clinical trials worldwide, while over 70,000 patients have been treated commercially in China. The company believes expanding development across multiple solid tumors will strengthen ivonescimab’s potential as a future treatment option for patients worldwide. Clinical site activation for the bladder cancer study is scheduled to begin later in 2026, with enrollment expected to follow as Summit advances its global registration strategy.
Source: Summit Therapeutics press release
